AmigaInput - The new Gaming-API for AmigaOS

From the viewpoint of a game programmer there is one area of the AmigaOS API, which has been behind the development of other operating systems since quite a while. I am talking about the area of the Input/Gaming APIs. In Windows there is DirectInput, in MacOS 9 there is InputSprockets - on AmigaOS we have a bunch of different APIs which are not compatible to each other and some hardware supports this API, some other hardware that API (lowlevel.library, gameport.device, psxport.device and several devices are even supported only by "direct hardware access").

For a game programmer that up to now meant either to only support some of the available input devices, or to write a lot of input handling code. When a new input device or adapter gets released it means that support for this needs to be explicitly added to the game instead of the user installing a new driver. This situation was of course unacceptable. So on the planning stages of OS 4 Hyperion Entertainment decided, that we need a Gaming-API for the Amiga. AmigaInput and its API have been designed and developed by Sven Ottemann, Hans-Joerg Frieden and myself, with additional work by Thomas Frieden. Christopher Kossa and myself have developed the Preferences GUI.

AmigaInput is a driver system consisting of a main-library and a set of drivers, which are actually AmigaOS 4 shared libraries. Every driver can implement a number of modules (for example the PSX Port driver implements the modules Classic_PSX, Classic_PSX_Digital, Classic_PSX_Wheel, Classic_PSX_Gun and Classic_PSX_Mouse). The naming scheme of these modules is as follows:

AmigaInput supports gamepads, mice and keyboards. Of course each type can be categorized into subtypes like Flightstick, Wheel, Joystick, and a lot of other subtypes.

A game, which would need to use an input device, would ask AmigaInput for a list of suitable devices. Providing a so-called enumeration-function to AmigaInput does this. This enumeration-function is provided by the developer of the game and specifies the requirements for the game (for example "Minimum number of buttons/axes" or "Needed device-type"). What data is available (axes, hats, buttons, coordinates,.) of course depends on the type of controller (a Joystick has different data available to a Mouse for example).

The core idea of AmigaInput is that a game does not need to know what sort of input devices are attached to the Amiga.
All sorts of devices would work with the game, and not a single line of code would need to be changed, in case a new input device becomes available. The only thing, which needs to be ensured, is that an AmigaInput-driver for the new device is developed. AmigaInput drivers contain very little code (the driver for analog-joysticks for example is sized only 7 KB) the main program logic is sitting in the main-library.

Screenshot 1 - AmigaInput Preferences

To give you a general idea of the system, screenshot 1 shows the Preferences-GUI of AmigaInput running. The drivers that are currently in development (most of them already fully completed) are:

All drivers are done fully in C-Code. It should be noted that the PSX Port driver is currently for Amiga Classic only, but we are investigating if it is possible to use the hardware (possibly with minor adaptations) in an AmigaOne and if there might be an AI_AmigaOne_PSX.library at one point. Thanks go to Joe Fenton who provided us with the full source-code of psxport.device, so that we could implement PPC Native PSX Port support for AmigaInput. I'd also like to thank Dreamworlds Development for information about the programming of the Amiga 4-Player-Adapter.

We might release further drivers - like for example for N64 or SNES or TurboGraphX gamepads using special adapters - at a later point, after the OS 4.0 release. People who are working on special adapters for certain kinds of controllers should be free to contact me at SteffenH@hyperion-entertainment.com, so that AmigaInput support for their hardware can be guaranteed.

Concerning mice and keyboards, these drivers support all mice and keyboards, which are supported by OS 4's input and keyboard.device.

Obviously as important as a good gaming API is that there is enough software, which actually uses this API. Of course all future PPC native Hyperion Entertainment titles will use AmigaInput for gamepad/mouse/keyboard support. At one point we will also release updates for our old titles, which will update them to OS 4 native binaries, which will also add AmigaInput support.

Screenshot 2

But of course there are old - mostly 68k - titles which might not get an OS 4 or even PPC version, especially games from the old Commodore times. In order to allow users to play these games on an AmigaOne (which after all does not have an AmigaClassic-style joystick-port) we developed a new version of the lowlevel.library, which internally uses AmigaInput. Screenshot 2 shows the Preferences GUI for the new lowlevel.library. Here you can set up lowlevel.library to use specific AmigaInput drivers. Obviously games, which directly "hit the hardware", won't work on an AmigaOne (though they still might work on an A4000 or A1200 running OS 4).

One immediate question users unfamiliar with OS 4 technology might have is "Wait a moment, isn't AmigaInput PPC Native, but those old games using lowlevel.library are 68k?" The trick is that the OS 4 Operating System will "detect" when a 68k program calls lowlevel.library and will ensure that the code "switches" into PPC Mode, calling the PPC Native lowlevel.library (and in effect the PPC Native AmigaInput). Generally AmigaInput will only work on Amiga's running Amiga OS 4. For OS 4 native Programs we actually recommend to no longer use lowlevel.library, but using AmigaInput directly, so that gaming controllers with analog mode or "more buttons" can be supported to their full capabilities instead of being limited to the capabilities of a CD32-Pad.

Steffen Haeuser
Hyperion Entertainment